#1 2005 vs #4 2011
Starters and Bench
On one level I think this would be an interesting game to watch. On the other hand 2005 strikes me as having too many weapons, depth and experience for 2011 to keep up. The only thing 2011 has going for it is the fact that was Roy Williams' best defensive team in his UNC tenure so far. 2011 posted an adjusted defensive efficiency of 90.4 which is slightly ahead of 2005's 91.7. The latter number is still pretty good in its own right. Williams has had four teams below 92.0 in adjusted defensive efficiency and these were two of them. The others were 2007 and 2012.
Even assuming 2011 can slow 2005 down offensively, 2005's defensive numbers are more than good enough to trip up 2011 on the offensive end. 2011 has the second worst adjusted offensive efficiency of the Williams era at 109.5 with only 2010 being worse. 2013 and 2014 are next at 110.9 and 111.7 respectively. The issue with 2011 was the lack of perimeter shooting. That team shot just 32.8% from three which ties 2010 for the worst perimeter shooting team of the Williams era. 2005 happens to be Williams' best perimeter team at 40.3% overall.
In short, 2005 should win and probably fairly handily.